This final rule revises the regulations for states to opt-out of the federal reformulated gasoline (RFG) program for areas where a state had previously voluntarily opted into the program. The previously published opt-out provisions provide that EPA-approved opt-out petitions become effective 90 days from approval. Under today's action, if a state has not submitted an opt-out petition to EPA by December 31, 1997, it must participate in the federal RFG program until December 31, 2003. The Agency believes this rule is necessary to ensure a smooth transition between the two phases of the reformulated gasoline program. The use of Phase II RFG will provide greater health benefits than Phase I by requiring further reductions from the refiners' 1990 gasoline baseline for volatile organic compounds (VOCs) and toxics by about 25% and 20% respectively. The requirements also include a nitrogen oxides (NO<INF>X</INF>) reduction of about 6%. Effective January 1, 2004, the current opt-out procedures become effective again. States that want to end their involvement in the federal RFG program prior to December 31, 1999, and not participate in Phase II of the program, must submit a complete opt-out petition to EPA by December 31, 1997. Today's action does not affect the regulations for opting in to the RFG program. In a separate action EPA will publish a final rule which would permit former ozone nonattainment areas to opt into the federal reformulated gasoline program.